fix to make mathjax work in notebook page

docs/javascripts/mathjax.js

@@ -1,12 +1,11 @@
 window.MathJax = {
   tex: {
-    inlineMath: [["\\(", "\\)"]],
-    displayMath: [["\\[", "\\]"]],
+    inlineMath: [['$', '$'], ["\\(", "\\)"]],
+    displayMath: [['$$', '$$'], ["\\[", "\\]"]],
     processEscapes: true,
     processEnvironments: true
   },
   options: {
-    ignoreHtmlClass: ".*|",
     processHtmlClass: "arithmatex"
   }
 };